In recent years, with the mobilization and high functionality of electronic equipments, the secondary battery, which is a power source, has become one of the most important parts. In particular, lithium (Li) ion secondary battery has become the mainstream in place of conventional NiCd battery and Ni—H battery, due to its high energy density obtained from the high voltage of the cathode active material and anode active material. However, Li-ion secondary battery by the combination of lithium cobalt oxide (LiCoO2)-type cathode active material and carbon-type anode active material mainly composed of graphite, which is currently used as standard Li-ion battery, is incapable of sufficiently supplying the amount of electricity required for today's high-functionality high-intensity electronic parts at a length of time, and is not able to fulfill the required performance as a portable power source. The theoretical electrochemical specific capacity of the cathode active material is generally small, and even those prospective new materials for future practical use remain to be of smaller values than the theoretical specific capacity of the current carbon-type anode active material. Further, the carbon-type anode, of which its performance has been rising little by little every year, is also approaching the theoretical specific capacity, and it is becoming impossible to anticipate large improvement in voltage source capacity with the current combination of cathode and anode active materials. There appears to be a limitation in meeting requirements for high-functionality and long mobile running of electronic devices, for loading on to industrial applications such as electric power tools, uninterruptible power sources, and electric storage devices, for which adoption is spreading, or for electric-powered vehicles.
Under such circumstances, metal-type anode active materials are being examined for application, as a method to dramatically increase the electric capacity than that currently possible, in place of the carbon (C)-type anode active material. Such method enables several to ten times the theoretical specific capacity of the current C-type anode. These utilize germanium (Ge), tin (Sn), and silicon (Si)-type materials as the anode active material. In particular, Si has a specific capacity that is comparable to that of metallic Li, which is said to be difficult to put to practical use, and is thus, being the center of study. Incidentally, the basic performance expected of a secondary battery is that the electric capacity retained by charging is large, and that this electric capacity is maintained as much as possible, even after usage cycles where charge and discharge is repeated. Even if its initial charge capacity is large, if the chargeable capacity or dischargeable capacity decreases immediately after repeated charge and discharge, its operation life is short, and its value as a secondary battery becomes low. However, in Si and other metal-type anode active materials, there is a problem in that their charge-discharge life is short. The cause of such problem lies in that the adherence between the current collector and the active material is small, and thus, as a means to solve this problem, specification of the surface configuration of the current collector, as well as compositions wherein the current collector component is diffused into or alloyed with the active material film, are being used (for example, see Patent Document 1 or 2). Further, by understanding the relationship between the dielectric layer on the surface of the current collector copper foil and the inverse of the electric double layer, the present inventors invented the copper foil for anode current collector for secondary battery (see Patent Document 3).